1. Field of the Invention
The present invention relates to an ultrasound diagnostic apparatus and a medical image-processing apparatus. The ultrasound diagnostic apparatus is an apparatus that transmits ultrasound to the inside of a subject using an ultrasonic probe, and obtains medical images of the subject based on waves reflected therefrom. The medical image-processing apparatus is an apparatus for processing medical images obtained by the ultrasound diagnostic apparatus. In particular, the present invention relates to the art used for comparative evaluation of motor functions of the same biological tissue obtained at different timing.
2. Description of the Related Art
The ultrasound diagnostic apparatus has a merit whereby it is possible to observe an image instantly by a simple operation such as the operation of simply placing the ultrasonic probe in contact with a body surface. Thus, the ultrasound diagnostic apparatus has been widely used to diagnose the shape and function of biological tissue. In recent years, more attention is being paid to an evaluation of a motor function of biological tissue, such as heart wall motion, and especially an evaluation of a three-dimensional motor function.
Additionally, the ultrasound diagnostic apparatus is used for obtaining images of biological tissue at a plurality of times at different timing (time and days), comparing such images, and thereby observing the time elapsed changes in condition of the biological tissue. A typical example of such a use includes stress echocardiography. Other than that, the ultrasound diagnostic apparatus is used in observation of a clinical course, preoperative/postoperative observation, and so on.
Stress echocardiography is an examination for evaluating the motor function of a heart by comparing an image obtained at a time when a patient is not subjected to stress such as motion or medication, with an image obtained at a time in which the patient is subjected to stress. There is also an examination for evaluating heart function by applying stress in stages and comparing images of the respective phases (e.g., refer to Japanese Unexamined Patent Application Publication No. 2005-304757).
In stress echocardiography using two-dimensional images, images are obtained from multiple views (tomographic planes) for each phase of the stress. Examples of such images include views such as an apical four-chamber view, an apical two-chamber view, a long-axis view of the left ventricle, and a short-axis view of the left ventricle.
Additionally, in recent years, stress echocardiography using three-dimensional images has been proposed. This method is to generate, at each phase of the stress, volume data by three-dimensionally scanning ultrasound, and obtain a desired cross-sectional image by subjecting this volume data to MPR (Multi-Planar Reconstruction).
However, regarding a conventional ultrasound diagnostic apparatus the following problems are pointed out. Firstly, there has been a problem in which stress echocardiography using two-dimensional images needs to variously change the way in which the ultrasonic probe is placed on the subject in order to obtain multiple images as described above, resulting in a complicated and long-time examination.
Secondly, although an image of the short-axis viewal view of the left ventricle is suitable for the observation of heart wall motion, it is possible in stress echocardiography using two-dimensional images, to obtain only short-axis tomographic images at the papillary muscle level, so that there has been a problem in which the condition of the left ventricle cannot be observed comprehensively.
Meanwhile, stress echocardiography using three-dimensional images is to obtain volume data at each phase to generate an MPR image and thus designate a cross-section that makes it possible to adequately observe the condition of the cardiac muscle. However, there has been a problem in which this operation is highly complicated and time consuming.
Additionally, because there has been no means for comparative observation by displaying both a past MPR image and a new MPR image, it has been particularly troublesome and time consuming to match a cross-sectional position of a past MPR image with a cross-sectional position of a new MPR image.
Furthermore, in the comparative observation, it is preferable to observe tomographic images at the same cross-section for each phase, but it has been difficult to set the same cross-section for each phase in a conventional configuration.
Moreover, even in the case of three-dimensionally scanning ultrasound, it is still necessary to place the ultrasonic probe properly on the subject in order to observe the condition of biological tissue. However, it is not possible to verify the manner of placement of the ultrasonic probe until an image is displayed for viewing.
Therefore, it has been particularly troublesome and time consuming to determine the manner of placement of an ultrasonic probe.
In addition, even in the case of observation of the clinical course, preoperative/postoperative observation, and the like, it has been difficult to designate the same cross-section for each timing when tomographic images based on volume data obtained at different timings are comparatively observed.